Thinking of cooling a Class A amp one would need something like double the power. One half for the amp, the other say 6A to cool it. I could be wrong as this is what I was thinking from looking at one of the datasheets.
They would perhaps be nice to cool a low power class A/B amp.

Hi gengis, I've used peltiers for cooling in several applications. They are heat pumps as you may know and work very well in situations where heat needs to be pulled away fast so that it can be dissapated more slowly via a large heatsink or by transferring the heat to a water cooling system away from the device being cooled. You can also use them to maintain a constant temperature via simple thermal feedback techniques. Large units are readily available on ebay and are dirt cheap compared to new.

Indeed, condensation is a BIG concern without the things Mr Evil brought up. Water cooling really isn't that scary if done correctly. I work on large frame lasers consuming 15kw of energy and running ~400v dc at 35A, and are water cooled. I've also water cooled several high energy projects of my own and have had great success. Amazing how much heat water can pull away.